Using one delegate to for several methods with different parameters.

Question

Hi!

Is it possible to use one delegate for several methods with different parameters somehow? I use reflection to get all the methods in a class, and I want to assign each of them a delegate and save that delegate in a dictionary with an enum as the key. This if for a remote procedure call implementation I'm working on so the enum is a command associated with a method.

Regards/Per

Answer 1

If the parameter count, order and type are the same, yes.

Simply put, a delegate is just a method signature.

Answer 2

You'd need a uniform way of passing them parameters. That means you'd need to pass them an array of parameters. And that means you need a MethodInfo, not a delegate.

Just store the MethodInfo against the name in the dictionary. Then when you need to call them, use the Invoke method to make the call, passing the target object and the array of parameters.

Answer 3

Something you could try is similar to the BCL's EventHandler delegate and the EventArgs parameter class:

Instead of directly passing all arguments to the delegate / method as parameters, you put them inside an object of some known base type and then you pass that object to the delegate:

class FooArgs { ... }

delegate void FooDelegate(FooArgs args);

Then, for all your methods requiring certain parameters, derive a new class from FooArgs that contains all the expected parameters.

(While this may seem like a detour, it's probably the only option since all your methods in the dictionary need to have the same "signature" as the delegate, i.e. same number of parameters, same parameter types, same return type.)

Answer 4

You could make a Dictionary<MyEnum, Object>;. After you extract the value, cast it to the appropriate delegate and invoke it.

Alternately, you could use something like the command pattern, and pass in commands rather than enumerated values:

interface ICommand
{
    void Execute();
}

class SomeCommand : ICommand
{
    public SomeCommand(/* instance and parameters go here */) { /* ... */ }

    public void Execute() { /* ... */ }
}

class SomeOtherCommand : ICommand { /* ... */ }

If you want them to be accessible like an enum, you could make a factory class w/ static methods to create your specific commands:

class RemoteCommand
{
    public static SomeCommand SomeCommand
    {
        get
        {
            var result = new SomeCommand(/* ... */);
            // ...
            return result;
        }
    }

    public static SomeOtherCommand SomeOtherCommand { get { /* ... */ } }
}

Edit:

Also, not sure of your needs, but exposing a list of method calls that the user might want to make, but abstracting out exactly what gets called sure sounds like an interface:

interface IRemoteCommand
{
    void RemoteMethod();
    void OtherRemoteMethod(/* params */);
    void ImplementedAgainstADifferentServerMethod();
}

Answer 5

You can use the Delegate.CreateDelegate Function and pass the appropriate delegate Type (Action<> or Func<>) and an instance of the MethodInfo, in this case you should construct the delegate type according to the MethodInfo parameters.